SHORT COURSE "PATTERN RECOGNITION" ABSTRACT: This course gives a short introduction into the field of automatic pattern recognition, with a special emphasis of pattern classification. First the motivation and the necessary terms are given, together with three illustrative examples. Then the groundwork is laid how to approach classification in a Bayesian probabilistic framework, introducing error, rejection and risk for decision making. The principal part deals with the different classifier architectures, model-based parametric Bayesian classifiers, Parzen windows, Nearest-Neighbor classifiers, Linear Discriminant Functions with one representative learning algorithm, the delta rule, which is extended to the generalized delta rule in the multilayer perceptron, radial basis function networks and polynomial classifiers. Dimensionality reduction is presented as an important preprocessing step in pattern recognition, consisting of feature selection and feature extraction. Feature selection search strategies are outlined together with the selection criteria. Feature extraction comprises Principal Component Analysis and Linear Discriminant Analysis. The topic of error estimation is used to measure the performance of a classifier. The Sammon map is used to visualize high-dimensional data. The text closes with the c-means clustering algorithm as a representative of unsupervised learning. A practical presentation of the theoretical concepts is included, using the 'TOOLDIAG' pattern recognition software. --------------------------------------------------------------------------- INDEX 1. MOTIVATION AND TERMINOLOGY Introduction Patterns, Pattern Recognition, Features and Classification Constraints Pattern classification and higher-level information processing Numerical features vs. symbolic features Probabilistic framework Time stationary patterns vs. dynamic patterns Basic Model of a Pattern Recognition System Nomenclature Examples of Pattern Generating Processes Example "Iris": Iris Flowers Example "Reactor": Fault detection in a chemical reactor Example "Vision": Object recognition in an industrial assembly task Further Reading Software Support 2. PROBABILISTIC FRAMEWORK FOR PATTERN CLASSIFICATION Bayes Theorem Bayes Decision Rule For Minimum Error Classification Bayes Decision Rule For Maximum Likelihood Classification Bayes Decision Rule For Minimum Risk Classification Inference and Decision Model Assumption and Parameter Estimation Model assumption Parameter estimation Assuming multivariate Gaussian distribution and estimating its parameters 3. CLASSIFIER MODELS, SUPERVISED LEARNING AND PROBLEMS Model-based Parametric Classifiers Parzen Windows The 1-Nearest Neighbor Classifier The K-Nearest Neighbor Classifier The Nearest Prototype Classifier Linear Discriminant Functions for Classification The Model Gradient Descent Learning and Least Mean Squared Error Generalized Linear Discriminant Functions for Classification Universal Function Approximators Curse of Dimensionality and the Bias-Variance Dilemma Polynomial Classifier Radial Basis Function Networks Multilayer Perceptron Architecture Delta Rule and Generalized Delta Rule 4. DIMENSIONALITY REDUCTION BY FEATURE SELECTION AND EXTRACTION Feature Selection Selection criteria Search strategies Limitations of Feature Selection Feature Extraction 5. ERROR ESTIMATION 6. HIGH-DIMENSIONAL DATA VISUALIZATION 7. UNSUPERVISED LEARNING BIBLIOGRAPHY